Here is the changelog for Windows 10 build 10586.240 (PC) and 10586.242 (Phone)

Microsoft released a surprise cumulative update for Windows 10 for PC and Windows 10 Mobile for those on the Release Preview Ring for the Insider Program. That ring is for some last minute testing before the general production release and is the safest of all the Insider levels.

Through the Feedback Hub Microsoft has posted the changelog. As it turns out, the PC version goes to build 10586.240 while the Mobile version heads to 10586.242. Having said that, the fixed and improved list is the same for both releases. Here is what's new.

Windows 10 build 10586.240 and .242 Cumulative Update

Improvements to general application compatibility.

Improvements in the upgrade experience, including fixing an issue where some devices would lose - data connections or touch input after upgrading to Windows 10.

There are likely some other under the hood changes not noted and so far the feedback has been very positive. We've successfully installed the update on our Verizon Lumia Icon, and everything is running very well with no issues.

For those the PC or tablet you can enroll in the Release Preview Ring by going to Settings > Update & Security > Advanced options > Get Preview Insider Builds. By default, after your device reboots, you will be in the Slow ring so you will want to move the slider to the left to get into Release Preview.

Enrollment in Release Preview is instant for phone and PC and the next time you check for an OS update, you will download tonight's cumulative update. The Release Preview ring has the lowest risk for PC and Mobile users and is considered generally safe to use on regular machines.

For those not who are not an Insider Microsoft will likely roll out this update to all Windows 10 devices and phones shortly and possibly on the next scheduled Patch Tuesday, which is May 10.